Electronic Speed Control System

ABSTRACT

A smart governor system that intercepts and adjusts throttle commands when certain criteria are met based on vehicle operations and a user-selected transmission mode. The governor, when engaged, reduces a throttle command in order limit engine and/or ground speed.

RELATED APPLICATIONS

This application is a continuation of and claims benefit of and priorityto U.S. patent application Ser. No. 16/278,661 filed Feb. 18, 2019entitled Electronic Speed Control System, which claims benefit of andpriority to U.S. Provisional Application Ser. No. 62/631,605 filed Feb.16, 2018 entitled Electronic Speed Control System, both of which arehereby incorporated herein by reference in their entireties.

FIELD OF THE INVENTION

The present invention pertains to electronic control of a utilityvehicle's speed using an electronic throttle control system.

BACKGROUND OF THE INVENTION

Most utility or sport recreational vehicles have a conventionaltransmission system in which the engine speed responds directly to athrottle command, regardless of the operating conditions. Though anexperienced user may appreciate having complete control over thethrottle response, there are numerous situations in which it may bedesirable to limit ground speed and/or engine rotations per minute (rpm)of a utility vehicle.

For example, if the utility vehicle is being used in a setting where itis desired to limit engine noise, such as a golf course, it may bedesired to set an upper limit on engine rpms. Another example may be ifthere is an attachment on the vehicle, such as a plow, it may be desiredto prevent the vehicle from going too fast and risk damaging the plow,the vehicle, or injuring the driver.

Many vehicles have a throttle ramp, which controls the rate at which anengine accelerates. However, throttle ramps do not typically limit topspeed or engine rpms. Some vehicles have a governor built in to limittop speed, but these are typically not “smart systems” that allow a userto select upper limits based on the activity and do not include afeedback loop that monitors actual ground speed.

In order to maximize the performance and utility of a vehicle in variouswork environments, it would be beneficial to have a governor system thatadjusts a throttle command sent by a user such that the adjustedthrottle command results in an engine response that fits a set ofdesired criteria.

SUMMARY OF THE INVENTION

The present invention includes a control system for speed compensationon a vehicle, also referred to herein as a traction system. The systemmay be incorporated onto a machine during production or it may beretrofitted onto existing vehicles.

One aspect of the invention provides an electronic transmission controlsystem for a vehicle that includes a speed compensation component, apedal command component, and a throttle actuator. The speed compensationcomponent is, in one embodiment, an algorithm that determines a maximumallowed speed for the vehicle based on whether or not the vehicle isoperating an attachment, and a position of a transmission selector;determines a machine ground speed; and calculates a governor throttleoffset value by comparing the maximum allowed speed and the machineground speed.

The pedal command component generates an electronic pedal throttlecommand based on a mechanical pedal position that is electronicallyadjusted according to a throttle ramp. The system applies the governorthrottle offset to the pedal throttle command to generate a finalthrottle position command, which is sent to the throttle actuator.

Another aspect of the invention provides a method of governing the speedof a vehicle using an electronic speed control system that involvessetting a maximum allowed ground speed based on a vehicle attachment ifthere is an attachment being used, or if there is not an attachmentbeing used, setting the maximum allowed ground speed based on a positionof the transmission. Next the maximum allowed ground speed is comparedto a machine ground speed to determine a governor throttle offset value.Then a pedal throttle command is adjusted with the governor throttleoffset value to generate a final throttle position command.

Still another aspect of the invention provides a method of calibratingan electrical zero throttle position of an electronic speed controlsystem of a vehicle to a desired engine rpm. This method includessetting the electronic speed control system to calibration mode, whichin turn commands an actuator to place a bell crank attached to athrottle cable against a mechanical stop. The mechanical stop is used asan initial zero throttle position. Next the ECU commands the actuator toslowly turn the bell crank to increase the throttle position and anengine rpm. During this time, the throttle position and the engine rpmare monitored using the machine electronic control unit (ECU). Thethrottle position is held when the manufacturer-recommended engine rpmis achieved, and the held throttle position is set as the calibratedelectrical zero throttle position.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of which embodiments ofthe invention are capable of will be apparent and elucidated from thefollowing description of embodiments of the present invention, referencebeing made to the accompanying drawings, in which

FIG. 1 is a flowchart of a speed compensation component of an embodimentof the invention;

FIG. 2 is a flowchart of a pedal command component of an embodiment ofthe invention;

FIG. 3 is a flowchart of a throttle calibration component of anembodiment of the invention;

FIG. 4 is a partial perspective cutaway view of a vehicle havingphysical components of the invention installed thereon;

FIG. 5 is a partial perspective cutaway view of a vehicle to illustratethe arrangement of a throttle cable, actuator shaft and bell crank of anembodiment of the electronic speed control system of the invention; and,

FIG. 6 is a front elevation of an embodiment of the actuator shaft andbell crank of the invention.

DESCRIPTION OF EMBODIMENTS

Specific embodiments of the invention will now be described withreference to the accompanying drawings. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art. Theterminology used in the detailed description of the embodimentsillustrated in the accompanying drawings is not intended to be limitingof the invention. In the drawings, like numbers refer to like elements.

Generally, the present invention provides a solution to theaforementioned needs by engaging a ground speed governor to create athrottle offset if certain ground speed governor conditions are met.These conditions are determined by the position of a user-controlled,transmission selector or whether an attachment is installed on thevehicle. For each position, different maximum allowed ground speeds areimplemented.

The ground speed governor continuously compares the maximum allowedground speed against the machine's ground speed and a throttle offset iscalculated. The throttle offset value is added to the throttle commandreceived from the user, such as via a throttle pedal or lever. When auser desires to accelerate the vehicle, the user actuates a throttlemechanism such as a throttle pedal, thumb lever, twist grip, etc. Forsake of clarity, the term “pedal command” or “pedal throttle command”will be used herein to denote the actuation of a throttle mechanism. Asthe pedal is depressed, the pedal position is converted to a throttlecommand, which is in turn relayed to the throttle ramp. The throttleramp is a setting that controls the rate at which the engine speedincreases, thereby controlling the behavior of the vehicle acceleration.When a non-zero throttle offset value (either a positive or negativenumber) is added to the pedal throttle command, a final throttle commandis calculated and sent to the throttle actuator.

In order to ensure system accuracy, one embodiment of the presentinvention includes a calibration sequence that ensures the throttlecommand corresponds to the pedal command. Various factors may warrantrecalibration, the most common of which is throttle cable stretch.

During normal operation, the throttle system uses an idle setting thatis fast enough to maintain the engine in an idling state while slowenough to minimize engine noise and ensure the transmission does notengage.

FIG. 1 is a flowchart of a speed compensation component 10 of anembodiment of the invention. The speed control system begins at 100 byfirst analyzing whether the transmission position 80 is in park orneutral. The transmission position 98 refers to the position of atransmission selector positionable by a user of the vehicle. A physicalembodiment of a transmission selector 400 is shown in FIGS. 4 and 5. Inat least one embodiment, the vehicle may include five differenttransmission selector positions. One skilled in the art will readilyunderstand that the number of transmission selector positions may bevariable, depending on the uses of the incorporating vehicle, withoutdeparting from the invention. The five positions of the vehicletransmission selector 400, used as an example herein, are Range High,Range Low, Reverse, Park, and Neutral.

If the transmission position 80 is in park at 102, or in neutral at 106,then the maximum speed is set to zero at 104 or 108, respectively. Ifthe transmission position 80 is not in park or neutral, then at 110 itis determined whether there is an attachment 90 engaged with thevehicle.

Attachments may include limitations on the maximum speed the vehicle maytravel. The determination of an attachment is made prior to furtheranalysis of the transmission position because if the attachment has aspeed limitation associated with it, that attachment speed limitationoverrides speed limitations associated with the transmission selectorposition.

If, at 110, it is determined that an attachment is engaged, then at 112the maximum speed for that attachment is used as input for the MaximumAllowed Ground Speed 126 to determine whether the Governor SpeedConditions are met at 140.

If, at 110, it is determined that an attachment is not engaged, then at101, the transmission position 80 is again analyzed to determine anappropriate Max Allowed Ground Speed 120.

The control system determines at 114, whether the transmission selectoris in the Range High position. If the control system determines that theselector is in the Range High position at 114, then at 116 the Max RangeHigh Speed value (for example, 25 mph) is used as input for the MaximumAllowed Ground Speed 126 to determine whether the Governor SpeedConditions are met at 140.

If at 114 the control system determines the transmission selector is notin the Range High position, the logic of the control system nextdetermines at 118 whether the transmission selector is in the Range Lowposition. If the control system determines that the selector is in theRange Low position at 118, then at 120 the Max Range Low Speed value(for example, 13 mph) is used as input for the Maximum Allowed GroundSpeed 126 to determine whether the Governor Speed Conditions are met at140.

If at 118 the control system determines the transmission selector is notin the Range Low position, the logic of the control system nextdetermines at 122 whether the transmission selector is in the Reverseposition. If the control system determines that the selector is in theReverse position at 122, then at 124 the Max Reverse Speed value is usedas input for the Maximum Allowed Ground Speed 120 to determine whetherthe Governor Speed Conditions are met at 140.

In order to determine whether the Governor Speed Conditions are Met at140, the input value for Maximum Allowed Ground Speed 126 is comparedagainst the Machine Ground Speed 130. The Machine Ground Speed 130 is acalculation made by the Ground Speed Converter 132. The Ground SpeedConverter 132 gets inputs from a sensor 134 which measures wheelrotation speed, and a defined rolling radius 136. Knowing the rollingradius of the wheels, the converter 132 is able to calculate groundspeed.

At 140, the conditions are met if the Machine Ground Speed 130 isgreater than the Maximum Allowed Ground Speed 120, indicating agoverning correction must be made, a load on the machine is not allowingthe maximum speed, or the expected acceleration, at the full stroke ofthe pedal position for a set amount of time, or if the throttle pedalposition changes drastically, allowing for a ramp down in speed ratherthan an abrupt stop. This is accomplished at 150 by applying a negativecorrection factor known as a Governor Throttle Offset 154. If theMachine Ground Speed 130 is not greater than the Maximum Allowed GroundSpeed 120, then at 152, the Governor Throttle Offset 154 is set to zero.The outputs from steps 150 and 152 are designated as A and B,respectfully, in FIGS. 1 and 2 to show they are used as inputs in thePedal Command 20 of FIG. 2.

Turning now to FIG. 2, the relationship between a Pedal Command 20 andthe Speed Compensation 10 is explained. The Pedal Command 20 begins witha mechanical position of the throttle actuation mechanism, in this casea pedal, at 200. Being an electronic system, the mechanical position ofthe pedal at 200 is converted to an electronic throttle command at 202.

Physically, the pedal 410 is shown in FIGS. 4 and 5. Electrical signalsfrom the pedal 410 position are measured by the ECU 420, which in turncontrols the actuator 430 according the method of the invention. Theactuator 430 is connected to a bell crank 440 (see FIG. 6) via anactuator shaft 450. The actuator 430 may be an electric motor, ahydraulic actuator, or the like. The bell crank 440 is connected to, andoperates, the throttle cable 460.

The throttle command 202 is next relayed to the throttle ramp at 204.The throttle ramp is a setting that controls the rate at which theengine speed increases, thereby controlling the behavior of the vehicleacceleration. Thus, the throttle ramp alters the desired throttlecommand 205 in accordance with a desired throttle response protocol. Theadjusted throttle command 205 is then sent as an input to a throttlesumming computation at 206. The computation at 206 adds the adjustedthrottle command 205 to the Governor Throttle Offset 154, which iseither zero, a negative value or a positive value. When a non-zerothrottle offset value (a negative number) is added to the pedal throttlecommand, a final throttle command 208 is calculated and sent to thethrottle actuator at 210. Physically the throttle actuator is theactuator 430 shown in FIG. 4.

FIG. 3 shows a Throttle Calibration Flow Chart 30 of the invention. Thiscalibration sequence ensures the throttle command corresponds to thepedal command. Doing so corrects any degradation in engine performancedue to throttle cable stretch. During normal operation, the throttlesystem uses an idle setting that is fast enough to maintain the enginein an idling state while slow enough to minimize engine noise and ensurethe transmission does not engage.

Beginning at 300, the system determines whether the user has elected toperform a calibration sequence via a manual calibration selector. If theselector is not in the calibration setting, normal machine operationresumes at 302. If, however, the selector has been set to calibration at300, at 304 a bell crank 440 is physically moved to a mechanical stop.Looking at FIGS. 4-6, this is accomplished by the ECU 420 commanding theactuator 430 to rotate until the edge 445 of the bell crank 440 impingeson the stop 470. This stop 470 represents an initial zero throttle forpurposes of the calibration sequence. This position thus becomes theelectrical zero throttle position for the throttle actuator during thecalibration sequence.

Next the calibration sequence begins at 306. From the electrical zeroposition, established by the mechanical stop 470, the actuator 430slowly increases the throttle position and the engine rpm. The machineECU 420 is monitoring the throttle position and engine RPM during thissequence.

Next, at 308, when the throttle position results in the desired engineRPM the ECU communicates to the throttle actuator 430 to stop thecalibration sequence and hold the desired position. The desired engineRPM is a machine-specific determination made by the manufacturer inorder to provide optimal engine response. By way of non-limitingexample, for a given machine, setting the desired engine RPM to 100 RPMhigher than idle may reduce or eliminate a dead band in throttleresponse. The optimal desired engine RPM is determined throughexperimentation.

Finally, at 310 the machine ECU 420 communicates a new calculatedcalibration position that is used by the throttle actuator 430 as thenew electrical zero position. After this the system is placed in aholding pattern at 312 and 314, until the operator takes the vehicle outof calibration mode, at which point normal machine operation is resumedat 302.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

1. (canceled)
 2. An electronic speed control system for a vehicle,comprising: a calibration selector; a mechanical stop; a throttleassembly including a throttle actuator having a throttle position; thethrottle assembly having a first component positioned to selectivelycontact the mechanical stop based on the throttle position of thethrottle actuator; an electronic control unit programmed to run an RPMcalibration algorithm based on the calibration selector, comprising:moving the first component of the throttle assembly against themechanical stop; determining an initial zero throttle position with theelectronic control unit based on the throttle position of the throttleactuator; increasing the throttle position of the throttle actuator andthereby increasing a corresponding RPM of an engine to a predeterminedRPM value; and, determining a calculated zero throttle position based onthe throttle position and the predetermined RPM value.
 3. The electronicspeed control system of claim 2, wherein the first component of thethrottle assembly is a lever.
 4. The electronic speed control system ofclaim 3, wherein the lever is a bell crank.
 5. The electronic speedcontrol system of claim 5, wherein the bell crank includes a first edgethat is configured to contact the mechanical stop.
 6. The electronicspeed control system of claim 5, wherein the throttle actuator isconnected to and configured to move the bell crank.
 7. The electronicspeed control system of claim 6, wherein the determining the calculatedzero throttle position is preceded by monitoring the throttle positionof the actuator and the RPM of the engine with the electronic controlunit.
 8. The electronic speed control system of claim 7, wherein thepredetermined RPM value is configured to reduce a dead band in throttleresponse.
 9. A vehicle with an electronic speed control system,comprising: a chassis; a ground engaging mechanism configured to supportthe chassis; an engine supported by the chassis; a mechanical stop; athrottle assembly including a throttle actuator having a throttleposition; the throttle assembly having a first component positioned toselectively contact the mechanical stop based on the throttle positionof the throttle actuator; an electronic control unit configured toexecute an RPM calibration algorithm, comprising: actuating the throttleactuator to move the first component against the mechanical stop;determining a physical zero throttle position based on the throttleposition of the throttle actuator; increasing the throttle position ofthe throttle actuator and thereby increasing a corresponding RPM of theengine to a predetermined RPM value; and, determining a calculated zerothrottle position based on the throttle position and the predeterminedRPM value.
 10. The vehicle of claim 9, wherein the first component ofthe throttle assembly is a lever.
 11. The vehicle of claim 10, whereinthe lever is a bell crank.
 12. The vehicle of claim 11, wherein the bellcrank includes a first edge that is configured to contact the mechanicalstop.
 13. The vehicle of claim 12, wherein the throttle actuator isconnected to and configured to move the bell crank.
 14. The vehicle ofclaim 9, wherein the determining the calculated zero throttle positionis preceded by monitoring the throttle position of the actuator and theRPM of the engine with the electronic control unit.
 15. The vehicle ofclaim 9, wherein the predetermined RPM value is configured to reduce adead band in throttle response.
 16. The vehicle of claim 9, whereindetermining the calculated zero throttle position further comprisesmaintaining the throttle position at the predetermined RPM value.
 17. Amethod of calibrating an electrical zero throttle position of anelectronic speed control system of a vehicle to a desired engine rpmcomprising: moving a first component of a throttle assembly against amechanical stop; determining an initial zero throttle position with anelectronic control unit based on the throttle position of a throttleactuator with an electronic control unit; increasing the throttleposition of the throttle actuator and thereby increasing a correspondingRPM of an engine to a predetermined RPM value; determining a calculatedzero throttle position based on the throttle position and thepredetermined RPM value with the electronic control unit.